Certain state of the art gas turbine engines utilize finned materials for fabricating the thermal liner wall. Examples of such liner construction are disclosed in U.S. Pat. No. 3,706,203 granted to Goldberg et al on Dec. 19, 1972, and U.S. Pat. No. 4,302,941 granted to DuBell on Dec. 1, 1981. The '203 patent discloses a type of liner that comprises a pair of spaced walls formed in cylindrical bodies and attached end over end in louver fashion to form the combustion chamber. Parallel walls extending in a grate-like fashion from one wall interconnect the other wall and define therewith a plurality of open-ended longitudinal passageways. Because of the louver construction, the upstream end of each liner element accepts cooling air from the cooling air supply, and discharges it from the downstream end thereof into the combustion chamber. Succeeding louver sections pick up and discharge the cooling air in a like manner.
The '941 patent discloses a modified construction of the liner disclosed in the '203 patent, by providing inlet openings intermediate the upstream and downstream ends of each liner element and conducting the cooling air in both counter and parallel flow relation to the combustion products within the combustor. Additionally, in the liner disclosed in the '941 patent, the parallel walls extending from the hotter wall do not interconnect the other wall, thereby allowing the hotter wall to "float" with respect to the cooler wall. This serves to reduce heat transfer to the cooler wall, thereby extending the life thereof. Further cooling is obtained by extending the downstream end of the floating wall to define a lip and thereby reestablish a film of cooling air for improved film cooling of the transition area between axially adjacent elements of the floating wall. Thus the lip at the downstream end of each floating wall element overlaps the upstream end of the floating wall element immediately downstream thereof.
One of the shortcomings of the floating wall liner disclosed in the '941 patent is that in order to remove a particular element of the floating wall, each of the elements upstream of that particular element must be removed first due to the overlapping lip of the upstream element. Therefore, if one element of the floating wall is damaged, a large number of elements may have to be removed in order to remove and replace the damaged element. Having to remove so many elements merely to replace a single element of the floating wall adds to the cost of maintaining the combustor and adds to the overall cost of operating the gas turbine engine that incorporates such liners.
What is needed is a liner for the combustor of a gas turbine engine in which a particular element of the floating wall can be replaced without necessitating removal of the elements immediately upstream thereof.